Domain Authority is in my opinion the single greatest indicator of a sites ability to compete organically for search traffic. It is a great question and its simply complex. Keep in mind Domain Authority or DA as we shall refer to it pretty much here on is the single best number to predict ranking ability and we know that the top 3 positions consume over half of all searches so it can be directly attached to traffic.

A few disclaimers: Domain Authority is not a Google creation it is from Moz.com and it is their educated guess at how